Non-invasive Estimation of Pulmonary Artery Pressure in Healthy Subjects by Electrical Impedance Tomography

Pulmonary hypertension (PH) is a condition characterized by a sustained elevation in pulmonary artery pressure (PAP) above 25 mmHg assessed by right heart catheterization. PH is fatal in absence of adequate treatment or therapy, as the condition progressively increases the workload of the right heart and ultimately leads to its failure. With a minimal indicative prevalence of 1 case/300, PH affects at least 25'000 people in Switzerland alone. After initiation of PH therapy, the follow-up of the patient's health status is often limited to punctual PAP measurements at the clinic at intervals of several months. The lack of more frequent measurements of the patient's PAP strongly hinders the identification of short-term trends in pulmonary hemodynamics, and therefore the anticipation of worsening conditions or treatment inefficiency. As possible solutions, wireless implantable hemodynamic monitors such as the CardioMEMSTM HF System (CardioMEMS Inc., Atlanta, USA) have recently been introduced for the continuous monitoring of PAP in patients with PH. The benefits of frequent measurements over intermittent clinic visits have been demonstrated in several previous studies, notably in terms of prediction of therapy outcomes, anticipation of worsening heart failure, feedback rapidity during therapy, or decline in hospitalization rates. Nevertheless, despite the undeniable advantages that implantable monitors offer to the patient, they remain highly invasive solutions. In contrast, noninvasive alternatives for the measurement of PAP exist, such as transthoracic echocardiography, but are impractical for frequent PAP assessments due to their dependency on qualified personnel to perform the measurement. An optimal PAP monitoring modality for patients with PH should be non-invasive (free of any risks or complications associated with cardiac catheterization) and unsupervised (able to operate without supervision of a medical doctor). Such a modality does not currently exist. In the